This research is directed towards the advancement of our understanding of the biomechanics of the hip and knee. The work involves a documentation of hip and knee mechanics in normal subjects, patients with degenerative joint disease, and patients with surgical reconstruction of their joints during a variety of daily activities. This research specifically involves the development of a three-dimensional model of the lower extremity including origin and insertion points of all muscles about the hip and knee (and selected muscles about the ankle) and origin and insertion points of knee (and ankle) ligaments. This model is utilized in an investigaton of various schemes to distribute calculated intersegmental resultant forces and moments about the hip and knee to the actual anatomic structures carrying those loads. A validation of this distribution investigation is being conducted in normal and pathological situations utilizing EMG recordings. This investigation will finally result in the collection and reporting of data on the mechanical function of the hip and knee which is necessary to rationally design, utilize, and evaluate various treatment modalities.